yes, but some people clean up their mailboxes. I know I do. Specially with something as spammy as FB email notification back in 2009. I did check my timeline and some messages there DO look like they HAD to be private - no way those kind of information would be posted on my wall. Unfortunately, i do not keep FB emails from 2009 anymore. I guess many can't prove because of this fact - deleted fb notifications from 2009/2008